Various means have heretofore been known to improve the color reproduction of color films in order to make the formed color image more faithful to an object and to enhance the sharpness of the formed color image. For instance, Japanese Patent Application (OPI) No. 2537/75 describes a method to use a DIR compound having an interlayer development inhibitory effect so as to make the reproduction of primary colors more highly pure and sharp (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"). In addition, another means is known for masking the deterioration of color reproducibility which results from the unnecessary side absorption of a coloring dye of a coupler used in a color film, by the use of a colored coupler. However, said known means are still defective in that it has not been possible in the color reproduction of neutral tints such as orange color or violet color to be faithful to the original object, although the color reproducibility of primary colors such as blue, green, and red colors have been improved. On the other hand, U.S. Pat. No. 3,672,898 describes specific definitions of the spectral sensitivity distribution of each of blue, green- and red-sensitive layers so as to improve the faithfulness of the color reproduction. However, this method is difficult to be practically applied to photographic materials for cameras for the following reasons:
The first reason is, when the spectral sensitivity of a red-sensitive layer is shifted to the range of short wavelengths and is thereby made to substantially overlap with the spectral sensitivity distribution of a green-sensitive layer, the sensitivity of said red-sensitive layer decreases. This is one defect. Said red sensitivity reduction is caused by the fact that the amount of light in the side of a short wavelength in the red-sensitive layer becomes insufficient due to the optical absorption of a sensitizer dye used in a green-sensitive layer which generally exists in the upper layers of said red-sensitive layer and the fact that the red-sensitive layer itself contains a magenta colored cyan coupler so as to correct the side absorption of a green color light of a coloring dye of a cyan coupler contained in said red-sensitive layer and therefore the amount of light in the side of a short wavelength in said red-sensitive layer also becomes insufficient due to the optical absorption of said magenta colored cyan coupler contained therein. In particular, in the case that a phenol type cyan coupler as described in Japanese Patent Application (OPI) No. 42045/83 and Japanese Patent Application (OPI) No. 204545/82 is used, the use of a magenta colored cyan coupler is essential and indispensable as the coloring dye in said phenol type cyan coupler has a large amount of said side absorption, and thus, the sensitivity reduction of the red-sensitive layer is remarkable in said case.
The second reason is, when each spectral sensitivity is made largely overlapped with each other, the distinguishability of neutral tints is made high but the chroma of primary colors is made lowered. This is another defect. In order to compensate for said chroma reduction, the interlayer development inhibitory effect is necessary to be made large as mentioned above. In practice, however, any sufficient effect could not be attained therefor in a conventional technique, for various reasons, including, for example, problems of accumulation of a released inhibitor which will lead to fluctuation of the characteristics of light-sensitive materials finally obtained after processing.
The present inventors have earnestly tried various experiments in order to overcome said defects in prior arts, and have now found the present invention which is free from said defects, as described in detail hereinbelow.